Console > SB Sound Card

I'm wondering if anyone can explain the different inputs that are present on the back of Sound Blaster sound cards...specifically an Audigy B800. I am trying to send a signal from a Mackie's main outs (1/4") into the Blaster. I hooked it into the mic input, but it is distorting wicked in Audition. I am not familiar with sound card operation, and thought that perhaps it was because the Blaster's mic input is set for mic level sources, but I have no idea if sound cards work that way. Now, if I send a very low signal level to the sound card, I get good-sounding audio at acceptable levels in Audition, but I'd like to set the Mackie up so I get good levels there, and then send that to the sound card. I have no idea what all the inputs on the sound card are (no manual). Any hints, tricks, tips, ideas, etc?